The investigators propose to continue the follow-up of 51,529 male health professionals, aged 40 to 75 years in 1986 to address a series of dietary hypotheses related to coronary heart disease, stroke, peripheral arterial occlusive disease, and cancers of the large bowel and prostate. During the initial funding period they have demonstrated that the study population has substantial variation in intake of a wide variety of nutrients, including fat intake that varies from 25 percent to 40 percent of calories for means of extreme quintiles. Most dietary variables are measured in this study by a semiquantitative food frequency questionnaire (SFFQ) developed and refined by the investigator's group over the last 14 years; detailed studies among a subsample of participants in this study indicate that this questionnaire has performed well; the average correlation between the questionnaire and 14 days of diet recording for 16 nutrients of interest was 0.66. Intake of selenium and other elements is assessed by nested case-control measurements using toenail clippings provided by 32,000 participants. Body fat distribution is assessed by waist and hip circumferences obtained in 1987. The first two-year follow-up cycle has been completed; the investigators received completed questionnaires from 96 percent of respondents and identified another 322 incident deaths (total follow-up equals 96.3 percent). The investigators plan to continue following the cohort by questionnaires mailed at two-year intervals to update exposure information and ascertain nonfatal events. Complete dietary assessments will be included every four years (1990-1994). All reported cases of nonfatal MI, stroke, peripheral arterial disease and cancer are documented with hospital records and/or pathology reports. Fatal events are ascertained with the National Death Index and documented using all available records. Based on rates of disease observed in the first follow-up cycle, during the eight years of follow-up represented by this continuation the investigators anticipate a total of 1,350 cases of fatal or non-fatal myocardial infarction, 322 cases of stroke, 409 peripheral arterial occlusive disease, 431 cases of large bowel cancer and 823 cases of prostate cancer. These events will provide substantial power to evaluate the specific hypotheses addressed in this proposal, and to describe quantitative dose-response relationships between dietary factors and incidence of cardiovascular diseases and cancer.